1. Technical Field
The present invention relates to a technology for preventing a direct-current component from being applied to pixels.
2. Related Art
In an electro-optical device which displays images by using an electro-optical material, such as liquid crystal, in order to prevent degradation of characteristics, the electro-optical material is driven by an alternating current. For example, in an active matrix-type liquid crystal device which uses a thin film transistor as a switching element, a substantially constant voltage is applied to a common electrode facing a plurality of pixel electrodes with liquid crystal therebetween, while a data signal having a voltage corresponding to a grayscale level of a pixel is cyclically polarity-inverted on the basis of a prescribed potential, and then is applied to each pixel electrode.
In such an alternating-current (AC) driving, if an effective voltage value to be applied to the electro-optical material is different according to a positive data signal and a negative data signal, the amount of light emitted from the electro-optical device cyclically changes, thereby causing a flicker. Further, a direct-current component may be applied, and thus the electro-optical material may be degraded. For this reason, a technology for adjusting the voltage of the common electrode (counter electrode) has been suggested, such that, when images are displayed, the cyclic change in the amount of light emitted from the electro-optical device is minimized, that is, the flicker is minimized (for example, see JP-A-8-286169)
However, this technology just performs automatic adjustment such that the flicker is minimized. That is, the above-described technology is, so to speak, a measure, but does not thoroughly improve a problem that effective voltage values of positive and negative polarities to be applied to liquid crystal are different.